The Molecular Cytogenetics Core Facility provides Cancer Center investigators cytogenetic and molecular DNA analysis of fresh cells and tissue, established and somatic cell lines, human tumors and mouse tumors, particularly those from transgenic mice. This Core is new since the last submission of this Cancer Center Grant and was developed at the request of members of Programs 1, 3, 5 and 6. Cytogenetic services consist of routine Giemsa (G)-banding and C-banding on fibroblast, lymphoblast or somatic cell hybrid lines for the purpose of determining karyotypes. The service also includes utilization of fluorescence in situ hybridization (FISH) for better clarification of these karyotypes, including both m-FISH (multicolor FISH) and SKY (spectral karyotyping), that uses 24 different colors to analyze chromosomal changes. FISH is also utilized to study chromosomal changes in interphase cells in tumors (especially in paraffin sections), in bone marrow transplants, and for chromosomal localization of genes. The molecular service of this Core consists of microsatellite analysis of tumors for loss of heterozygosity, mutation analysis of tumors, and chimerism studies of bone marrow transplants. In some instances to perform the services, tissue culture services are needed and include: general growth, maintenance, and freezing of patients? cell lines; transformation of lymphocytes to generate permanent lymphoblast lines; preparation of DNA from cell lines and peripheral blood; and generation of somatic cell lines as needed. In other instances, to perform the services, new, specialized services including comparative genomic hybridization (CGH) and chimerism analysis have been developed. These analyses have been facilitated by the addition of two computer-assisted microscopy units and a DNA sequencer. In response to user requests, the facility actively develops new technology in molecular cytogenetics.